Congenital irreducible atlantoaxial dislocation associated with cervical intramedullary astrocytoma causing progressive spastic quadriparesis.

Simultaneous presence of congenital irreducible atlantoaxial dislocation (AAD) and cervical intramedullary astrocytoma has not been previously described and may cause disabling myelopathy. This 55-year-old lady presented with suboccipital pain, spastic quadriparesis, Lhermitte's phenomenon and sphincteric disturbances. Lateral radiographs and magnetic resonance imaging showed irreducible AAD, occipitalized atlas, C2-3 fusion, and,an intramedullary tumor from C2-5 level iso-to-hypointense, non-enhancing, except in a small segment in the dorsal C2 level. A suboccipital craniectomy with C2-5 laminectomy revealed a greyish-white tenacious tumor. The tumor was decompressed using a C2-5 midline myelotomy and duroplasty. An occipitocervical lateral mass fixation was performed. Histopathology revealed a low-grade astrocytoma. At three-month follow-up, her spasticity had decreased and quadriparesis and sphincteric disturbances were persisting. Postoperative lateral radiographs and intrathecal contrast CT scan showed a stable occipitocervical construct. Thus, the suboccipital craniectomy and laminectomy with midline myelotomy and duroplasty facilitated space for progressively expanding intramedullary astrocytoma with irreducible AAD; the lateral mass fixation provided stability at the craniovertebral junction.

Occipitocervical contoured rod stabilization: Does it still have a role amidst the modern stabilization techniques?

Background: The occipitocervical contoured rod (CR) stabilization for use in craniovertebral junction (CVJ) pathologies is an effective and economical technique of posterior fusion (PF). Aims: The various indications for CR in CVJ pathologies are discussed. Settings and Design: Retrospective analysis. Materials and Methods: Fifty-four patients (mean age: 31.02 +/- 13.44 years; male: female ratio=5.75:1) who underwent CR stabilization are included. The majority had congenital atlantoaxial dislocation (AAD; n=50); two had CVJ tuberculosis; one each had rheumatoid arthritis and C2-3 listhesis, respectively. The indications for CR fusion in congenital AAD were associated Chiari 1 malformation (C1M) (n=29); occipitalized C1 arch and/or malformed or deficient C1 or C2 posterior elements (n=9); hypermobile AAD (n=2); and, rotatory AAD (n=3). Contoured rod as a revision procedure was also performed in seven patients. Most patients were in poor grade (18 in Grade III [partial dependence for daily needs] and 15 in Grade IV [total dependence]); 15 patients were in Grade II [independent except for minor deficits] and six in Grade I [no weakness except hyperreflexia or neck pain]. Results: Twenty-four patients improved, 18 stabilized and six deteriorated at a mean follow-up (FU) of 17.78 +/- 19.75 (2-84) months. Six patients were lost to FU. In 37 patients with a FU of at least three months, stability and bony union could be assessed. Thirty-one of them achieved a bony fusion/ stable construct. Conclusions: Contoured rod is especially useful for PF in cases of congenital AAD with coexisting CIM, cervical scoliosis, sub-axial instability and/or asymmetrical facet joints. In acquired pathologies with three-column instability, inclusion of joints one level above the affected one by using CR, especially enhances stability.